Global Responses of Gravity Waves to Planetary Wave Variations during SSWs Observed by SABER

2015 AGU Fall Meeting


December 17, 2015
8:00am to 12:20pm
San Francisco, CA


Abstract: This study describes the global responses of observed gravity waves (GWs) to winter planetary wave (PW) variations during stratospheric sudden warmings (SSWs) using TIMED-SABER temperature measurements. GWs affect the ionosphere and thermosphere, and it is important to understand global variations of GWs from the lower atmosphere to the thermosphere during SSWs in order to advance our understanding of vertical coupling. The responses of GWs to SSWs are shown by calculating correlations between vertical components of Eliassen-Palm (EP) fluxes in the winter polar stratosphere and global GW temperature amplitudes derived from SABER observations. Consistent with previous ground-based and satellite observations, winter EP fluxes show positive correlations with GWs in the winter hemisphere. More interestingly, winter stratospheric EP fluxes are positively correlated with GWs in the tropics and in the summer mesosphere, indicating global variations of GWs in response to PW variations in the winter hemisphere. To study the mechanism of GW response to SSWs, global wind simulations from SD-WACCM are used. Zonal wind anomalies (differences in the wind before and during SSWs) extend from the winter stratosphere to the summer mesosphere. By comparing anomalies in background winds to the observed patterns in the correlations between GWs and winter EP fluxes, we find that regions of positive correlation follow change in background winds and zero-wind lines. The results indicate that responses of SABER GWs in the summer hemisphere to winter PW variations during SSWs are likely caused by changes in GW propagation due to the changes in atmospheric circulation. These observed changes in global GWs during SSWs can affect the ionosphere and thermosphere, and studying global GW variation during SSWs is important for understanding mechanisms of vertical coupling.


Chihoko Cullens

BIDS Alum – BIDS Data Science Fellow

Chihoko Cullens was an assistant research physicist at the Space Science Laboratory at UC Berkeley. Her primary research interest was understanding the atmospheric coupling process between different atmospheric layers and its impact on ozone recovery, climate change, and space weather predictions. She worke on understanding how small-scale features in the atmosphere affect the atmospheric coupling process using high-resolution atmospheric simulations as well as observational data from various satellites and ground-based installations.